Lubricant



Patented May 25, 1948 LUBRICANT Eugene Lieber, New York, N. Y., and Aloysius F.

Cashman, Bayonne, N. J., assignors to Standard Oil Development Company, a corporation of Delaware No Drawing. Original application January 1,

1942, Serial No. 425,351. Divided and this application June 6, 1944, Serial No. 539,010

Claims. (Cl. 252-483) 1 This invention relates to the field of lubricants and more particularly to stabilized extreme pressure lubricants.

It is known that plain mineral oils do not have a sufiiciently high film strength for lubricating moving metal parts which contact each other under high pressures, such as certain types of bearings, engines, gears, etc. It is also known that the film strength or load-carrying capacity of such mineral oils can be greatly increased by adding thereto various chemical compounds or materials containing active halogen and/or sulfur, and sometimes phosphorus, but these various materials, although very effective in carrying the high loads demanded of extreme pressure lubricants, have a serious disadvantage that during storage, especially in contact with certain metals such as iron, the undergo some type of degradation or change which tends to make-certain constituents thereof insoluble and precipitate out.

It has now been found that the addition of small amounts of certain types of materials to the extreme pressure lubricating agents or, to the lubricants in which they are compounded, will stabilize them against such tendencies to form an insoluble precipitate or sediment, With this primary object in view, another object of the invention is to accomplish this desired stabilization without interfering or materially reducing the extreme pressure lubricating characteristics of the lubricant and without materially increasing the corrosive tendencies of such lubricants toward metals with which they come in contact.

Broadly, the invention comprises adding to such extreme pressure agents from which an insoluble precipitate or sediment tends to settle out during storage, a small amount of a stabilizer comprising a low molecular weight aromatic compound having not more than two nuclei condensed together in One radical and having not more than 2/1: nuclear substituents, Where n equals the number of nuclei condensed in one radical.

Numerous types of aromatic compounds come within the scope of this invention; for instance. among the aromatic hydrocarbons which can be used may be included mono-nuclear aromatic compounds such as benzene, andvarious monoor di-alkyl substituents thereof such as toluene, xylene, amyl benzene, para-cymene, etc., as well as compounds containing two or more separate mono nuclear groups such as di-phenyl and the like, and compounds containing two condensed nuclei such as naphthalene and various monoalkyl derivatives thereof such as amyl naphtha- 2 lene, or partially hydrogenated derivatives such as di-hydro naphthalene and thedimer or other lower polymers of di-hydro naphthalene. Ether and sulfur derivatives of such aromatic hydrocarbons may also be used such as diphenyl oxide, beta naphthyl ethyl ether, thiophenol, sulfanilic acid, phenothiazine, etc. Certain other types of aromatic derivatives may be used such as butyl 4 phthalate or phenolphthalein.

Thus, it is one of the primary objects of the invention to use a cyclic compound, of the class described, as an addition agent to the extreme pressure agent per se in order to stabilize the latter against insolubilizing degradation during storage. Another feature of the invention is the use of such stabilizing compounds in blends of a mineral or hydrocarbon lubricating oil base stock containing an extreme pressure agent normally soluble therein and therefore already dissolved therein.

The amount of'the stabilizer to be used according to this'inventlon should normally be within the approximate limits of about 1% to 15%. preferably about 2% to 10%, about 5% having been found very suitable, based on the weight of extreme pressure agent, or about 0.1- 3%. preferably about Oil-2.0% based on the total lubricant. e

The extreme pressure lubricant to which the above-described stabilizers may be added according to this invention, may be prepared by incorporating into a mineral oil base stock derived from any of the commonly used crude petroleum oils a. compound containing active halogen and a compound containing active sulfur, or one or more compounds containing both halogen and sulfur in the same molecules. The invention is particularly applicable to extreme pressure lubricants containing corrosive chlorine compounds, for instance, chlorinated aliphatic or aromatic hydrocarbons such as chlorinated derivatives of paraffin wax, kerosene, aromatic petroleum fractions, or coal tar solvents, The amount of chlorine to be used will of course depend upon the severity of the conditions under which the lubricant is to be used but will generally vary between the approximate limits of 5% and in the chlorinated organic compounds, or between the approximate limits of 1% and 10% based on the total weight of lubricants. The incorporation of sulfur compounds tends to increase the suitability of the lubricant for use under high temperatures, and the sulfur compounds to be used may be, for instance, sulfu-rlzed fatty or mineral oils such as sulfurized sperm oil,

the active or combined state, on the basis of the.

extreme pressure lubricating agent per se, or about 0.5% to 10% based onthe total lubricant.

Instead of using separate chlorine compounds and sulfur compounds, it is possible to use single materials in which both sulfur and halogen have been incorporated. For instance, a suitable raw material such as paraflln wax or aliquid petroleum distillate such as kerosene, maybe treated with a sulfur halide such aasulfur monoor dichloride, in order to incorporate both sulfur and chlorine. generally preferred commercially because it permits better technical control is to chlorinate' a suitable raw material such as paraflln wax, kerosene, or naphtha, to the desired chlorine content, and then subsequently treat the resultant compound with sulfur or an inorganic sulfide such as sodium sulfide or polysulflde, or a mixture thereof with sulfur and sodium hydroxide, or an organic sulfur compound such as thiocarbonate or xanthate.

One example of a suitable extreme pressure a lubricating agent is one made by chlorinating kerosene to a chlorine content of about 25% to 50%, such as 35%, by passing chlorine through kerosene at a temperature of about 175 to 200 F., and adding to the resultant chlorinated kerosene an isopropyl alcohol solution of aqueous caustic soda and sodium hydrogen sulfide containing free sulfur admixed therewith, using a reflux temperature for a reaction time ranging between about hour and 5 or hours. The

resultant product may, for instance, contain 7.0%

sulfur and 33% chlorine, or, as another example, might contain 6.5% sulfur and 31% chlorine. Ordinarily, the stabilizers of this invention will be needed more, and therefore be of greatest advantage when extreme pressure lubricating agents are used which contain a large amount of sulfur and chlorine.

A compound made by this method and having this latter composition will be referred to as "Extreme pressure agent A, in the tests reported herebelow.

Another example of an extreme pressure lubricating agent which may be used is one made by similarly chlorinating kerosene to a chlorine content of about to 50%, preferably about 2 to and treating the resultant chlorinated kerosene with sodium xanthate, as, for instance, in alcohol solution. The sodium chloride forms and separates out, and the liquid product is distilled free of alcohol, leaving a product, for example, which may contain 9% sulfur and 32% chlorine.

Extreme pressure lubricants made by adding to a lubricating 011 base stock separate chlorine and sulfur compounds may be made, for instance,-

by using about 10% by weight of chlorinated paraffin wax containing 40-50% of chlorine and 10% of sulfurized sperm oil containing 10% sulfur.

A different method and one which is The mineral oil base stock may be obtained soluble or it may be one to which has been added an aromatic. liquid, such as a solvent extract, to solubilize the extreme pressure agent in the oil.

The following tests will further explain how the invention is carried out and will also lllus-' trate the advantages of th invention.

5% (by weight) blends were made of a large number of aromatic compounds coming within the scope of this invention, in a commercial sample of Extreme pressure (E. P.) agent, the preparation of which has been described hereinabove. Each of the resulting blends was split into two parts. one part being placed in a glass container, and the other into a similar container having therein a strip of boiler plate unpolished sheet mild steel (the same as used in tanks) These containers were then placed in an oven thermostatically controlled at F. for 24 hours. As a control test, the original Extreme pressure agent A was placed in similar containers, 1. e., with and without a strip of steel, and was subjected to a storage temperature of 150 F. for 24 hours. 1

In order to determine the extent of quality degradation as regards solubility in mineral oil, the samples of E. P. agent A which had undergone test as described above, after cooling to room temperature were blended to 10% (by weight) in a Panhandle bright'stock to form a series of four extreme pressure lubricants. These blends were allowed to stand at room temperature Naphthalene Di-hydro naphthalene Dimer of di-hydro naphthalene Para-cymene Beta-naphthyl ethyl ether Diphenylene oxide Sulfanilic acid' Phenothiazine In the control sample of E. P. agent A, a large amount of sediment was observed both in theplain glass container and in the glass container having the iron (steel) present. In all of the other tests in which the stabilizers listed above were used, little or no sediment or precipitate was present at the conclusion of the test, thus indi-- cating that the aromatic hydrocarbons as well as the ether, sulfur and partially hydrogenated derivatives thereof coming within the scope of this invention, all were effective in stabilizing the extreme pressure agent against development and settling out of an insoluble precipitate or sludge during storage under severe test conditions. 7

.Some of these stabilizers were dissolved in a mineral lubricating oil base stock and then sub- Jected to similar storage tests, and they were found satisfactorily efiective in stabilizing the lubricant against insolubilizing degradation during storage.

Although the theory as to the exact mechanism of the operation of the invention is not well understood, it is'believed that the stabilizer of this invention tends to prevent a self-polymerization of the extreme, pressure agent to a heavier and insoluble form during storage. The extreme pressure agent may selectively react with the sta- 76 bilizer to form a soluble but still effective extreme pressure molecule instead of reacting with itself to form a higher molecular weight insoluble product.

In preparing extreme pressure lubricants according to this invention, other known addition agents may be incorporated if desired, for instance, fatty oils, soaps of fatty acids or naphthenic acid, other materials having thickening, viscosity-index improving and pour-depressing properties, anti-oxidants, oil-soluble metal soaps, dyes, etc.

It is not intended that this invention be limited to any of the particular examples which have been given merely for illustration, nor by any theory as to the mechanism of the operation of the invention, but only by the appended claims in which it is intended to claim all novelty inherent in the invention as well as other modifications coming within the scope and spirit of the invention. I

This application is a division of application Serial No. 425,351, filed January 1, 1942, now Patent 2,363,880.

It is claimed:

1. An extreme pressure agent comprising a halogenated petroleum hydrocarbon containing active halogen and sulfur, normally tending during storage to undergo degradation leading to the formation of ingredients which are insoluble in paraflinic mineral oils, also containing a small amount of a stabilizer consisting of a low molecular weight aromatic compound containing a single monocyclic aromatic hydrocarbon group of the formula 'CeH4, the residue of the molecule being composed of atoms selected only from carbon, hydrogen, and oxygen.

2. Product according to claim 1 in which the extreme pressure lubricating agent contains about 550% of chlorine and about 130% of sulfur and is derived by chlorinating a petroleum hydrocarbon fraction and treating the resultant chlorinated hydrocarbon material with a sulfurizing agent.

3. An extreme pressure agent consisting essentially of a halogenated petroleum hydrocarbon containing active halogen and sulfur and normally tending during storage to undergo degradation leading to the formation of ingredients which'are insoluble in paraflinic mineral oils, to which has been added a small amount, suflicient to stabilize against such degradation, of monocy clic aromatic hydrocarbon having the general formula C6H4R2 in which R is selected from hydrogen and alkyl groups having 1-5 carbon atoms.

4. An extreme pressure agent consisting essentially of a halogenated petroleum hydrocarbon containing active halogen and sulfur and normalwith a sodium polysulflde sulfurizing agent, to

which extreme pressure agent has been added a small amount between the approximate limits of about 1-15% by weight of ,para-cymene, said amount being suilicient to stabilize against such degradation.

EUGENE LIEBER. v ALOYSIUS F. CASHMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,203,944 Brown June 4, 1940 2,298,638 Prutton Oct. 13, 1942 

